# Pyrefly: Meta's New Type Checker for Python

Meta has announced [Pyrefly](https://pyrefly.org), a new static type checker built in Rust to deliver fast performance and scalability for large Python codebases.

While inspired by Meta’s earlier tool [Pyre](https://pyre-check.org), Pyrefly is not a rewrite: it’s a clean-slate implementation with a new type inference engine, a custom incremental computation model, and cross-platform support.

Despite the maturity of tools like [mypy](https://pydevtools.com/handbook/reference/mypy.md), [pyright](https://pydevtools.com/handbook/reference/pyright.md), and Pyre, Meta found that scaling static analysis across massive codebases required a faster, more flexible foundation. Pyrefly is designed to deliver instant IDE feedback with strong type inference.

This comes right as Astral, the team behind [uv](https://pydevtools.com/handbook/reference/uv.md) and [ruff]((https://pydevtools.com/handbook/reference/ruff.md)), prepare to release [Red Knot](https://pydevtools.com/blog/early-explorations-of-astrals-red-knot-type-checker/), their fast typechecker also written in Rust.